• International conference on construction engineering and project management
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• 2009.05a
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• pp.869-875
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• 2009

Safety is a big issue in the construction sites. For safe and secure management, tracking locations of construction resources such as labors, materials, machineries, vehicles and so on is important. The materials, machineries and vehicles could be controlled by computer, whereas the movement of labors does not have fixed pattern. So, the location and movement of labors need to be monitored continuously for safety. In general, Global Positioning System(GPS) is an opt solution to obtain the location information in outside environments. But it cannot be used for indoor locations as it requires a clear Line-Of-Sight(LOS) to satellites Therefore, indoor location monitoring system could be a convenient alternative for environments such as tunnel and indoor building construction sites. This paper presents a case study to investigate feasibility of Wi-Fi based indoor location monitoring system in construction site. The system is developed by using fingerprint map of gathering Received Signal Strength Indication(RSSI) from each Access Point(AP). The signal information is gathered by Radio Frequency Identification (RFID) tags, which are attached on a helmet of labors to track their locations, and is sent to server computer. Experiments were conducted in a shield tunnel construction site at Guangzhou, China. This study consists of three phases as follows: First, we have a tracking test in entrance area of tunnel construction site. This experiment was performed to find the effective geometry of APs installation. The geometry of APs installation was changed for finding effective locations, and the experiment was performed using one and more tags. Second, APs were separated into two groups, and they were connected with LAN cable in tunnel construction site. The purpose of this experiment was to check the validity of group separating strategy. One group was installed around the entrance and the other one was installed inside the tunnel. Finally, we installed the system inner area of tunnel, boring machine area, and checked the performance with varying conditions (the presence of obstacles such as train, worker, and so on). Accuracy of this study was calculated from the data, which was collected at some known points. Experimental results showed that WiFi-based indoor location system has a level of accuracy of a few meters in tunnel construction site. From the results, it is inferred that the location tracking system can track the approximate location of labors in the construction site. It is able to alert the labors when they are closer to dangerous zones like poisonous region or cave-in..

• The Journal of Korean Academic Society of Nursing Education
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• v.2
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• pp.75-94
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• 1996

This survey study was aimed at identifying the degree of educational need of the KNOU(Korea National Open University) nursing students defined as admission purposes, satisfaction of distance learning education, learning methods, and courses after graduation. Among randomly assigned 1000 students, 320 KNOU nursing students who allowed to participate in the study completed the questionnaires. The data were analyzed using descriptive statistics, chi-square test, and t-test, Results of this study were as follows : 1. The admission purposes of the KNOU nursing students were 'in order to get a bachelor's degree(83.8%)', 'to acquire knowledge for task(61.3%)', or 'to be admitted for the graduate school (53.1%)' etc. Comparing the admission purposes by age, tow items- 'to explore new possibilities for myself' and 'excellent curriculum' showed statistically significant differences. These two items were also found to show significant differences by marital status. 2. For the media maintenance, the results showed that students use their own cassett radios(96.3%), VTR(49.4%), TV only for the study (44.1%), personal computer (3.31%), or joining Hitel (6.3%). 3. Listening rates of the radio lecture were 'over 80%(9.1%)', '50-80%(9.1%)', '20-50%(18.1%)', 'below 20%(30%)' and 'never(33.1%)', And record lecture showed listening rates as follows : 'over80%(17.2%)', '50-80%(15.9%)', '20-50%(24.4%)', 'below 20%(27,2%)' and 'never(14.4%)'. 4. The difficulties with KNOU life were 'listening radio lectures(38.8%)', studying by following teaching schedules (37.8%)', 'isolated self-study(10.3%)', and 'appearance in the attending classes(8.1%)'. 5. As for satisfaction with teaching methods, the data showed that 81.2% of the respondents were satisfied (or very satisfied) with 'attending classes' and 75%, with 'paper lectures'. On the other hand some of respondents were very dissatisfied with 'recorded lecture(12.8%)' and 'radio lecture(10.9%)' 6. The results also showed that the students want to have 'video conferencing lecture(77.2%)', 'cable TV(64.1%)' and 'CD ROM program' to improve learning effects. 7. Concerning learning attitudes, 48.8% of the students reported 'study mainly for examnination', and only 4.1% answered 'study every day with plan'. The learning attitude showed significant differences by marital status and age. The students also evaluated themelves as 'study very hard(5.9%)', 'study hard in general(41.6%)', 'study a little(40.3%)' and 'study little(11.9%)'. 8. The students responded the most effective learning material was the 'textbook (92.2%)'. 9. For the purposes of using the local center, the results showed 'for the attending classes(76.3%)', 'for the use of references(14.7%)', and 'for the study group(66.7%)'. 10. The results revealed that 20.3% of the respondents had ever experienced unregistration or temporary withdrawal, and 53.4% among them did not register more than one time. The most common reason for the unregistration was 'due to family affairs or their job (70.8%)'. 11. 88.1% of the respondents answered 'they will graduate without fail'. 12. Regarding the benefits from the KNOU graduation, respondents indicated 'graduate school admission(38.1%)', 'self-confidence in social life(17.5%)', and understanding social problems (10.9%)'. 13. 64.4% of the students showed that they have intention to enter the graduate school. The item 'changing work place' showed statistically significant differences by marital status and age.

• Journal of the Society of Disaster Information
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• v.10 no.4
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• pp.583-597
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• 2014

Fire caused by heater has various causes as many as the types of heater. also, lots of damage of human life and property loss are caused, since annually continuous fire accident by heater in traditional market is frequently occurring. There are not many cases of fire due to heater in most of residential facilities such as general house, apartments, etc., because they are supplied with heating boiler, however the restaurant, store and office of the market, sports center, factory, workplace, etc. still use heater, e.g. oilstove, electric heater, etc., so that they are exposed to fire hazard. Also, when investigating the number of fire due to heater, it was analyzed to occur in order of home boiler, charcoal stove, oilstove, gas heater/stove, electric stove/heater, the number of fire per human life damage was analyzed in order of gas heater/stove, oil heater/stove, electric heater/stove, briquette/coal heater. Also, gas and oil related heater were analyzed to have low frequency, however, with high fire intensity. Therefore, this research aimed at considering more scientific fire inspection and identification approach by reenacting and reviewing fire outbreak possibility caused by combustibles' contact and conductivity under the normal condition and abnormal condition in respect of ignition hazard, i.e. minimum ignition temperature, carbonization degree and heat flux along with it, due to oilstove and electric stove, which are still frequently used in public use facility, traditional market, and, of which actual fire occurrence is the most frequent. As the result of reenact test, ignition hazard appeared very small, as long as enough heat storage condition is not made in both test objects(oilstove/electric stove), however carbonization condition was analyzed to be proceeded per each part respectively. Eventually, transition to fire is the ignition due to heat storage, so that it was analyzed to ignite when minimum heat storage temperature condition of fire place is over $500^{\circ}C$. Particularly, in case of quartz pipe, the heating element of electric stove, it is rapidly heated over the temperature of $600^{\circ}C$ within the shortest time(10sec), so that the heat flux of this appears 6.26kW/m2, which was analyzed to result in damage of thermal PVC cable and second-degree burn in human body. Also, the researcher recognized that the temperature change along with Geometric View Factor and Fire Load, which display decrease of heat, are also important variables to be considered, along with distance change besides temperature condition. Therefore, the researcher considers that a manual of careful fire inspection and identification on this is necessary, also, expects that scientific and rational efforts of this research can contribute to establish manual composition and theoretical basis on henceforth fire inspection and identification.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.30 no.3A
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• pp.297-307
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• 2010

Recently, maintenance engineering and technology for civil and building structures have begun to draw big attention and actually the number of structures that need to be evaluate on structural safety due to deterioration and performance degradation of structures are rapidly increasing. When stiffness is decreased because of deterioration of structures and member cracks, dynamic characteristics of structures would be changed. And it is important that the damaged areas and extent of the damage are correctly evaluated by analyzing dynamic characteristics from the actual behavior of a structure. In general, typical measurement instruments used for structure monitoring are dynamic instruments. Existing dynamic instruments are not easy to obtain reliable data when the cable connecting measurement sensors and device is long, and have uneconomical for 1 to 1 connection process between each sensor and instrument. Therefore, a method without attaching sensors to measure vibration at a long range is required. The representative applicable non-contact methods to measure the vibration of structures are laser doppler effect, a method using GPS, and image processing technique. The method using laser doppler effect shows relatively high accuracy but uneconomical while the method using GPS requires expensive equipment, and has its signal's own error and limited speed of sampling rate. But the method using image signal is simple and economical, and is proper to get vibration of inaccessible structures and dynamic characteristics. Image signals of camera instead of sensors had been recently used by many researchers. But the existing method, which records a point of a target attached on a structure and then measures vibration using image processing technique, could have relatively the limited objects of measurement. Therefore, this study conducted shaking table test and field load test to verify the validity of the method that can measure multi-point displacement responses of structures using image processing technique.